poj 1915 Knight Moves(双向广搜)

#include<stdio.h>
#include<string.h>

#define maxN 1000000
#define maxM 310
int dir[8][2]={1,2,-1,2,1,-2,-1,-2,2,1,2,-1,-2,1,-2,-1};
int n,sx,sy,ex,ey;
int xx[maxN],yy[maxN];
int vist[maxM][maxM],map[maxM][maxM];

int abs(int x){return x<0?-x:x;}
int min(int x,int y){return x<y?x:y;}
int fun()
{
memset(vist,0,sizeof(vist));
memset(map,0,sizeof(map));
int head=0,tail=0;
xx[tail]=sx,yy[tail++]=sy,vist[sx][sy]=1;
xx[tail]=ex,yy[tail++]=ey,vist[ex][ey]=2;
while(head!=tail)
{
int x=xx[head],y=yy[head++],t=map[x][y];
for(int i=0;i<8;i++)
{
int r=x+dir[i][0],l=y+dir[i][1];
if(r<0||r>=n||l<0||l>=n)
continue;
if(vist[r][l]!=vist[x][y]&&vist[r][l]&&vist[x][y])
return map[x][y]+map[r][l]+1;
if(!vist[r][l]){
vist[r][l]=vist[x][y],map[r][l]=t+1;
xx[tail]=r,yy[tail++]=l;
}
}
}
}

int main()
{
int t;
scanf("%d",&t);
while(t--)
{
scanf("%d",&n);
scanf("%d%d%d%d",&sx,&sy,&ex,&ey);
if(sx==ex&&sy==ey)printf("0\n");
else printf("%d\n",fun());
}
}